1. Technical Field
The present disclosure relates to an organic light emitting device (OLED) and to a method of preparing the same, and more particularly, an OLED including: a substrate, a first electrode, a second electrode and an organic layer interposed between the first electrode and the second electrode, wherein the organic layer includes a first layer including an organic-metal complex.
2. Description of the Related Art
Organic light emitting devices (OLEDs) have beneficial brightness, driving voltage, and quick response characteristics, and can realize multi color display. Due to the above-mentioned benefits, a large amount of research into OLEDs has been carried out.
Typically, an OLED has an anode/organic emission layer (EML)/cathode structure. However, the OLED can also have various other structures, such as an anode/hole injection layer (HIL)/hole transport layer (HTL)/EML/electron transport layer (ETL)/electron injection layer (EIL)/cathode structure or an anode/HIL/HTL/EML/hole blocking layer (HBL)/ETL/EIL/cathode structure.
Materials that may be used in OLEDs can be classified into either vacuum depositable materials or solution coatable materials according to a method of preparing an organic layer. The vacuum depositable materials may have a vapor pressure of about 10−6 torr or greater at the temperature of about 500° C. or less and be low molecular materials, such as for example, having a weight average molecular weight of about 1200 or less. The solution coatable materials may be highly soluble in solvents to be prepared in solution phase, and include aromatic or heterocyclic groups.
When an OLED is manufactured by vacuum deposition, costs may be high due to expensive vacuum systems and high resolution pixels may not be easily manufactured if a shadow mask is used to prepare pixels for a natural color display. On the other hand, an OLED can be manufactured relatively easily and inexpensively using a solution coating method such as inkjet printing, screen printing and spin coating and can have relatively high resolution compared to when using a shadow mask.
However, properties such as thermal stability and color purity of materials available for the vacuum deposition may be superior to those available for the solution coating. Furthermore, even though the solution coated materials have beneficial thermal stability and color purity, the solution coated materials in the organic layer may crystallize to have a particle size capable of scattering visible rays which in turn may cause white turbidity or may have pin holes thereby deteriorating the OLED.
As properties of the conventional materials that are used to form an organic layer may not meet desired levels, there is a need to develop a material having benefical properties.